/Engine/Source/Runtime/HeadMountedDisplay/Public/IXRSystemAssets.h
NOTE: Not all XR systems support every EControllerHand value. If that's the case, then this will return an invalid device ID, though that specific value is undetermined and up to each XRSystem for interpretation.
A device ID that is specific to this XRSystem (can only be interpreted by other members belonging to the sameIXRSystemIdentifier)
int32 GetDeviceId ( EControllerHand ControllerHand )